Biomedical Engineering Reference
In-Depth Information
magnetic fi eld. By exploiting not only the ability to remove magnetic nanoparticles
from solution with an external fi eld, but also the ability to tailor the surface func-
tionality of the nanoparticles through synthetic means, it is possible to both sepa-
rate and detect - with great sensitivity - a wide range of analytes. In this chapter,
attention will be focused on the attachment of small molecules, polymers, and
biomolecules (e.g., nucleic acids and proteins) for the purposes not only of separat-
ing the target analyte from complex samples containing interferents, but also of
detecting them when the separation is complete. Some selected examples will also
be presented of the application of functionalized magnetic nanoparticles for
sensing and detection. Thus, the aim is to demonstrate the effi cacy and future
potential of magnetic nanomaterials for the effective preconcentration and sensing
of environmentally relevant analytes from complex matrices such as river, ground,
and ocean water.
9.2
Synthesis and Functionalization of Magnetic Nanoparticles
9.2.1
Synthetic Strategies for Magnetic Metal Oxide Nanoparticles
For the majority of sensing applications described in this chapter, the selection of
a magnetic nanomaterial containing specifi c attributes to enable the best sensing
performance is vital. Variations in nanoparticle core size, shape, and surface func-
tionality may often have dramatic effects on the performance of the material in
sensing applications. A wide range of synthetic methods is available to produce
nanoparticles with properties desirable for use in separation and preconcentration
applications [4, 5, 14, 16, 17, 21-24]. Such properties include:
•
An ability to specifi cally functionalize the nanoparticle with small molecules or
biological molecules so that they have a chemical affi nity toward the analyte of
interest.
•
A high magnetic susceptibility, so that they might be easily captured or
manipulated after being placed in contact with the sample of interest.
•
A high dispersibility in the sample of interest (typically aqueous systems).
•
Paramagnetic or superparamagnetic characteristics to prevent any irreversible
magnetic agglomeration of the nanoparticles in solution, while still enabling
magnetic recovery and manipulation.
- Fe
2
O
3
) have shown the most promise as
potential environmental magnetic sensing materials, as the synthesis, tuning of
physical properties, and surface functionalization of these materials have been
so well established. With this in mind, details of the more common methods of
iron oxide nanomaterials synthesis have been summarized here, with a special
Iron oxide nanoparticles (Fe
3
O
4
and
γ
